The following is a tabulation of some prior art that presently appears relevant:
U.S. PatentsPat. No.Kind CodeIssue DatePatentee1,865,453A1932 Jul. 5Louis Baltzley
U.S. Pat. application PublicationsPublication No.Kind CodePubl. DateApplicant20050145760A12005 Jul. 7Necia Bower, Peter Heller
Foreign Patent DocumentCntry Kind Foreign Doc. No.CodeCodePub. DtApp or Patentee102062303CNA2011 May 18—201251093CNY2009 Jun. 3—102012111927DEB32013 Dec. 24Patentinhaber Gleich